Effect: 

The magician asks for a volunteer from the audience. 

The volunteer picks a number between 1 and 10. 

The magician writes the number on a sugar cube. 

The magician drops the cube into a cup of water and holds the volunteer's hand over the water.

He/she turns the volunteer's hand over and Poof! the number is on the volunteer's hand.

Supplies:

~a pencil (must be a pencil, pen will NOT work)
~a sugar cube (you can have several for effect)
~a glass of water

Secret:

Have the volunteer pick a number. 

Write it onto the sugar cube with a pencil (press hard). 

Then, hold the cube between your thumb and one finger. 

Hold it so the number transfers onto your thumb and say," Now I will put this cube into the cup". 

Press the cube as hard as possible so the number is on your thumb. 

Put the cube into the water and hold the volunteer's hand above the water, make sure your thumb is in their palm so the number from your finger transfers onto the volunteer's hand. 

This is a good trick to show smaller kids because they are less likely to figure out the trick.